摘要
Exposure of the brain to cadmium ions (Cd 2+ ) is believed to lead to neurological disorders of the central nervous system (CNS). In this study, we tested the hypothesis that astrocytes, the major CNS-supporting cells, are resistant to Cd 2+ -induced injury compared with cortical neurons and microglia (CNS macrophages). However, treatment with CdCl 2 for 24 h at concentrations higher than 20 μM substantially induced astrocytic cytotoxicity, which also resulted from long-term exposure to 5 μM of CdCl 2 . Intracellular calcium levels were found to rapidly increase after the addition of CdCl 2 into astrocytes, which led to a rise in reactive oxygen species (ROS) and to mitochondrial impairment. In accordance, preexposure to the extracellular calcium chelator EGTA effectively reduced ROS production and increased survival of Cd 2+ -treated astrocytes. Adenovirus-mediated transfer of superoxide dismutase (SOD) or glutathione peroxidase (GPx) genes increased survival of Cd 2+ -exposed astrocytes. In addition, increased ROS generation and astrocytic cell death due to Cd 2+ exposure was inhibited when astrocytes were treated with the polyphenols compound ellagic acid (EA). Taken together, Cd 2+ -induced astrocytic cell death resulted from disrupted calcium homeostasis and an increase in ROS. Moreover, our findings demonstrate that enhancement of the activity of intracellular antioxidant enzymes and supplementation with a phenolic compound, a natural antioxidant, improves survival of Cd 2+ -primed astrocytes. This information provides a useful approach for treating Cd 2+ -induced CNS neurological disorders. © 2007 Wiley-Liss, Inc.